Category: Linux Tech

DNS client configuration can be handled by the standard Router Advertisement Daemon (radvd) – apt-get install radvd Edit /etc/radvd.conf on your Linux Router and insert the following at the end of the file to use Google’s DNS Caching server: RDNS 2001:4860:4860::8888{}; On your Linux clients install rdnssd. To automatically insert the advertised IPv6 DNS servers

IP packet drop can be easily emulated on any section of network using a Linux Bridge and a single iptables command:
iptables -t mangle -A FORWARD -m statistic --mode random --probability 0.01 -j DROP
(where probability is expressed as a value between 0 and 1)

It is often useful to place a Linux system on a specific network cable, to packet sniff or modify the network behaviour. The network setup: [switch] - ethernet cable - [node] becomes: [switch] - ethernet cable - [[Linux Bridge]] - ethernet cable - [node] The only requirement for the Linux Bridge is two physical network

With some bash scripts it can be useful to have them exit as soon as a command fails. To accomplish this have the following just after the “#!/bin/bash” line:
set -o errexit
This will cause the script to…

On my previous laptop I suffered with repeated over-heating problems whenever CPU load went high for a prolonged period. After several emergency shutdowns (performed by ACPI) I discovered the problem: cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor returned the result: “performance” Inserting the following line before the ‘exit’ line in /etc/rc.local: echo "conservative" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor resolved the problem. For all

When reading/writing a disk image using Linux tool ‘dd’ launch as follows:
dd if=/dev/sdb of=filename.img & pid=$!
this will run ‘dd’ in the background.
To see the progress:…

Search and replace in vi is both quick and simple:X,Ys/search/replace/g (where x – start line number, y – end line number. optional) One very useful feature is the ability to use parts of the search regular expression within the replace string. For example, where the selected lines contain values between 2000-2999 and all these values